Proportional spacing apparatus



Dec. 22, 1953 E. FREY ET AL 2,663,399

PROPORTIONAL SPACING APPARATUS Filed March 15, 1952 2 Sheets-Sheet l/NVEN 70?.9

Dec. 22, 1953 E. FREY ET AL PROPORTIONAL SPACING APPARATUS 2Sheets-Sheet 2 Filed March 15, 1952 Patentecl Dec. 22, 1953 UNITEDSTATES PATENT OFFICE 'PROPORTIONAL SPACING APPARATUS Erik-Frey andRussell E. Hattis, Chicago, 111.

Application March 15, 1952, -Serial N o."276,849

Iii-Claims. I

This invention "generally relates to :typewriting machines and, moreparticularly this invention relates to proportional .spacing apparatus.for use with typewriting machines.

One object of this invention is to provide an improved'spacing apparatuswherein the spacing produced is proportional to thesize of the lettertyped.

Another object of the instant invention is to provide a novelproportional spacing apparatus which may be used to .readily convertconventional fixed spacing typewriters to proportional spacingtypewriters.

Still another object :of the instant "invention is to provide a noveland improved proportional spacing apparatus which operates throughelectrical relays to move the carriage of :a typewriter.

A further object of the instant invention is to provide a novel andimproved apparatus which provides both proportional front and backspacing for a typewriter.

Another object :of @the :instant invention is to provide a novel andimproved variable spacing mechanism which also provides for adjustableline spreading in a typewriter.

A still further object of the instant invention is to provide a noveland simpleswitch mechanism for actuation by the character keys of aproportional spacing typewriter to energize electrical apparatus whichcontrols the movement of the carriage which in turn controls the spacingbetween the printed letters. 1

Other objects of the instant invention will -become apparent upon makingreference to the specification which follows and the drawings wherein:

Figure 1 shows aside view of the apparatus of one embodiment of theinstant invention added to a conventional fixed spacing typewriter;

Figure 2 is a rear view of a portion of the apparatus shown in Figure 1;

Figure 3 shows the switch actuating apparatus which is operated directlyby the character keys of the typewriter .of Figure 1;

Figure eshows a modificationoi the apparatus of Figure 3;

Figure 5 shows a sample wiring diagram for the operation .of the relaymechanism shown in Figures 1 and 2;

Figure 6 shows a modification of the relay ac tuation mechanism shown inFigures 1 and 2;

:Figure 7 shows an improvement over the relay mechanism shown in Figures1 and 2;

Figure 8 is a view of a portion ofthe apparatus of Figure 7 in adifferent operating condition than there shown.

The description that follows will describe several embodiments of theinstant invention as applied to the conversion of a conventional fixedspacing typewriter to a proportional spacing typewriter with a minimumof effort and expense. It should be understood however that theinvention may be incorporated into a typewriter as manufactured. Also,numerous modifications maybe made of the specific and preferredembodiments of the instant invention without deviating from the broadergeneric aspects of the instant invention.

In the drawings to be described, the parts of the conventional fixedspaced typewriter to which the invention is applied in the drawings havebeen omitted for purposes of simplification with only the outlinethereof shown in dotted lines. The parts, which must be added to theconventional fixed spacing typewriter to adapt it for proportionalspacing, are shown in solid lines. Also, like reference numerals in theseveral figures represent the same elements.

The conventional fixed spacing typewriter generally includes a rackfixed to the carriage and a pawl which normally engages the rack. The

force for moving the carriage is generally provided by a spring which isplaced under tension when the carriage is manually moved to its startingposition. The pawl engages the rack "until a character or spacing key isstruck. Then the pawl is released from engagement with the rackmomentarily which allows the carriage to move under the force of thespring at a fixed amount which is independent of the size of the letterstruck. Such a typewriter also includes a lever which frees the rack ofthe carriage from engagement with the pawl above mentioned. Then thecarriage may be freely translated by hand. Such a lever will behereinafter referred 'to as the carriage release lever.

Since all of these above elements are conventional and well known, thedetailed description thereof has been-omitted.

The present invention makes it possible to simply convert a fixedspacing typewriter to a proportional spacing typewriter which spaces theletters of a word an amount proportional to the size of the letters ofthe word. Thus, for example, when the character hey printing the letter1' is struck, the carriage will be moved, say, one unit; while when thecharacter key printing the letter w is struck, the carriage will bemoved, six units. Such a carriage action saves paper as well asproviding printed matter having a much more desirable appearance.

Thereare numerous proportional spacing typewriters in the prior art, butnone have the simplicity of the instant invention which makes itpossible to readily convert fixed spacing typewriters to proportionalspacing typewriters. Also, the existing proportional spacing typewritersdo not provide for automatic proportional back spacing or haveadjustable line spreading features which are as simple and eifective asthe line spreading mechanism which is to be hereinafter described.

One feature of the instant invention comprises mounting a rotatable feedscrew on the frame portion of a fixed spacing typewriter and con-.necting an arm to the carriage which rides in the groove of the threadof the feed screw. A ratchet gear mechanism is connected to the end ofthe feed screw and is used to impart rotary motion to the screw. Theratchet mechanism is operated by an electromagnetic device which movesthe ratchet mechanism an amount pro portional to the energized conditionof the electromagnet. The energization of the electromagnet iscontrolled by sets of electrical contacts which are actuated by the keysof the typewriter. The electromagnet may include a plurality of separatewindings which when separately energized impart a different amount ofmotion to the ratchet gear mechanism. The carriage release leverabove-mentioned is held in a depressed condition so that the position ofthe carriage is under the control of the feed screw. The particularwindings which are energized is dependent upon the size of the letterjust typed so that variable spacing is provided.

Referring now to the drawings, and Figures 1 and 2 in particular, oneembodiment of the invention comprises a relay apparatus or electromagnetI3 having three separate windings which may be energized eitherseparately or together in various combinations by the key mechanism (3,4, etc.) of the typewriter I. A switch unit 2 is placed under the keymechanism of typewriter I. In the example shown in Figures 1 and 2, thisswitch unit includes six switch actuation strings or threads I I whichclose respective switch contacts (not shown) connected to each threadwhen the threads are placed under tension. The threads are placed undertension when engaged by projections, such as 8, I0, and I, dependingfrom the arms of the character or spacing keys, such as 3 and 4, of thetypewriter. Normally these projections do not engage the threads II.When a particular character key is depressed, however, one or more ofthreads II are placed under tension, as shown in Figure 3, which closesone or more pairs of switch contacts associated therewith. The closingof a switch couples a suitable voltage source (such as the conventionalA. C. line voltage) to one or more of the windings of electromagnet I3.The magnetic force developed in electromagnet I3 attracts a rack wheelactuation lever arm I4 an amount which is dependent on the windingsenergized. Lever arm IE, which pivots about a pin II, includes anextension I5 made of a magnetic material which is attracted toelectromagnet I3, thus pulling down the end of lever arm I4 an amountpropor tional to the magnetic force developed by electromagnet I3. Eachwinding of electromagnet I3 provides a diiferent amount of force whenenergized. Pivoted to the end of lever arm I 4 is a rack or pawl member23 which includes an upper offset U-shaped portion including a firsttoothed portion 24 normally engaging a first gear 3| and a secondtoothed portion 26 on the other side of gear SI and axially displacedtherefrom which is normally adjacent to but disengaged from a secondratchet gear SI. Ratchet gears 3| and 3| are fixedly connected to aspiral lead screw 33 which is normally engaged by a carriage arm 22riding in the spiral groove of lead screw 33. Screw 33 is rotatablysupported in bearings such as 33 connected by brackets to the ends ofthe stationary frame portion 6!) of the typewriter. Arm 22 extends fromcarriage 59 which carries the typing paper and moves across the front ofthe stationary frame portion 60 of the typewriter. As ratchet gears 3|and 3| are rotated by rack or pawl arms 24 and 26 respectively, the leadscrew is rotated within bearings 63, etc.; and depending upon thedirection of rotation thereof, the carriage arm 22 and carriage 59 maybe moved in either the forward or backward direction. The carriage must,of course, be freed from engagement with the carriage rack pawlpreviously referred to. This is accomplished by keeping the carriagerelease lever iI depressed. This may be accomplished by means of a screw40 which is attached to the typewriter by a bracket 42 held in place bya nut 43 (see Figure 1).

The teeth of ratchet gear 3! are adapted to be rotated in a direction byrack arm 24 which will move the carriage 59 to the left as viewed fromthe front of typewriter I for forward spacing. Rack member 23 isnormally held in an upper position by a spring 25 which operates againstthe force of electromagnet I3. Energization of electromagnet I3 bydepression of a character or spacing key pulls down arm I4. Aselectromagnet I3 is de-energized as the operator lets go of thecharacter key, spring 25 will pull rack arm 2 back into its normalposition causing rotation of ratchet gear 3|. Because of the shape ofthe teeth of the ratchet gear 3! and rack arm 2|, the downward motion ofrack 23 will not impart motion to wheel 3| to prevent any back spacingof carriage 59 when the character key is depressed. Only the upwardmotion of the rack will rotate gear 3I. The amount of retation ofratchet gear 3| is dependent upon the distance the lever arm I4 ispulled downward by electromagnet I3. Rack arm 26 and ratchet gear 3ioperate in a similar manner to ratchet 3| and rack arm 24 justdescribed. The direction of the extent of the gear teeth on gear 3I' andrack arm 26 is reversed, however, to provide for back spacing. A lever 3pivoted about point 28 is actuated by the back space key '5. Thusdepression of back space key 5 depresses one end of lever B which causesthe other end 29 thereof to be raised. Connected to the end 29 of lever6 is a transverse rod 62 (shown in dotted lines in Figure 2 since it maynot actually be seen from the back of the typewriter) which rides in aslot 21 in rack arm 26. As transverse rod 62 moves upward, it pressesagainst the side of slot 21 thereby pivoting rack 23 about pivot pointI9 at the end of lever arm I4. This action pushes rack arm 26 inengagement with ratchet gear 3 I and disengages rack arm 24 fromengagement with ratchet gear 3!. Then when a character or spacing key,such as 3 or 4, is depressed, the electromagnet I3 is energized andlever arm I4 is pulled down an amount determined by the key pressed.Ratchet gear 3 I is rotated in a counterclockwise direction as viewed inFigure 1, as the character key is released which de-energizeselectromagnet I3. This rotates screw 33 in a direction to move carriage59 backwards for the back spacing operation. The procedure for backspacing therefore is to hold the back space lever down with the fingerof one hand and. then to depress and release the character key whichcorresponds to the letter previously typed. This returns the carriage tothe same position. it was in before the last letter was typed.

In order to prevent the typing of a letter during the back spacingoperation, an arm member may be connected to transverse rod 62. A thinplate member is attached to the end of arm member 39 so that as armmember 30 is raised with transverse rod 82, the plate member 35 israised in front of the type bar (not shown). Plate. member 35 slidesbehind type bar guide member 3? in the embodiment shown in Figure 1. Ifthe typewriter has a dead key or mimeograph key mechanism which preventsthe printing of a character as a key is struck, the back space. key maybe adapted to operate the dead key or mimeograph key mechanism.

Since the force of the relay provides the force for moving the carriage,if desired, the forward movement of the carriage may be used to store upenergy in a conventional typewrite tapespring apparatus comprising acylindrical housing 5? and a flexible spring tape 58 which tends to winditself within housing 5?. The energy used to store up energy in thespring is used for the purpose of returning the carriage to its ini tialposition. Thus, as the carriage moves to the right as viewed from therear of the typewriter as seen in Figure 2, the spring 53 is unwoundfrom housing 58 and is placed under tension much in the same manner asin conventional typewriters except that in such typewriters, the springtension is used to aid the forward motion rather than the backwardmotion of the carriage. The position of such a spring apparatus in themore conventional typewriter need only be reversed in position toconvert same into the typewriter machine shown in Figure 2.

As shown more clearly in Figure 1, a return key 44 is provided to raisethe carriage arm 22 to disengage it from the carriage screw 33. Arm 22swivels relative to an upper arm member 2| which is directly connectedto carriage 59 as by a suitable bracket Zl. The upper arm member 2I- ismade to swivel relative to bracket 2| by means of any suitable meanssuch as a nut-and-bolt arrangement 22"--5l passing through holes in thearm member 2! and bracket 21. A similar nut-and-bolt arrangement may beused for the swivel connection between carriage arm member 22 and armmember 2|. Carriage return key 44 is coupled to a lever 45 which pivotsabout a fixed shaft 4'! so that a downward movement of key 44 producesan upward movement of the end '43 of lever 55. Endportion 48 isconnected to carriage arm 22 as by a screw 53 so that the depression ofcarriage return 44 raises arm 22 from engagement with screw 33 by aswivel motion.

To provide for line spreading, the point about which ratchet wheelactuation lever arm [4 pivots is made variable. For a given attractiveforce developed by electromagnet I3, the amount of movement of the freeend of lever Hi depends upon the point about which lever h! pivots. Abracket I8 is connected to frame portion of typewriter l in any suitablemanner and includes a plurality of threaded holes in which a pin I! maybe threaded. Lever M has a slot I 6 formed therein with a series ofspaced rounded notched portions $6 in the top portion thereof which areplaced opposite the threaded holes 6 in bracket H1. The edges of theslots rest on the top of pin 11 when placed adjacent thereto and leverI'4 pivots about pin Ils. If'it is'desired' to spread a given line asmall amount to even up the margin, then pin IT is moved to the? nextnotched position.

Refer now to Figure 3 which discloses the manner in which the relayenergizingcontactsare closed in: response to depression of a characteror spacing key. A thread it is shown suspended within container 2 shownvin Figure l bymeans of suitable spacers 19, 80, etc. The other threadsare similarly supported. When a characterikey 3 is depressed, theprojection in presses-downward on thread ll putting it undertensio'n. sothat contact 16 of normally openedv contact-pair Hi -I8 is efiectivelypulled into engagement with contact. 18 thus completing. anelectrical'circult (shown in Figure 5) which energizes -one-of.--thewindings. of electromagnet I 3-. Figure 4 shows an alternative but. lesspreferred manner of closing, the relay energizing contacts: In thisembodiment, a separate bar 82 replaces each of the threads; shown-inFigures 1 and 3*. Asin the apparatus shown in Figure 3, each key isprovided with projections such as Ill-Which actuate. the particular barplaced beneath it which will actuate the desired windingofselectromagnet 3; The bars may be held in a raised position by aspring such as 86 at each end thereof which extends upwardly from a.spring housing such as 83 having a hole therein to receive theassociated spring. Each bar includes anextension such as 84 carrying anelectrical contact on the end thereof such as 81 which is normally held;out of contact with another electrical contact such as 89 by'theassociatedyspring. Depres sion of a character or spacing key depressesthe appropriate bar by means: of the extension connected to thedepressed key bar such as: 9, and the electrical contacts operated bythe particular bar are closed thereby energizing electromagnet' l3.

Reference isnow made to Figure 5-which shows the circuit diagram of theenergizing-circuit for electromagnet or relayl3. The three windings ofelectromagnet [-3 are shown as windings 13a, i317, and. I30,respectively. Each winding is coupled to a suitable voltage sourcethrough a-connector plug 90 and contactsof various switches now to bedescribed. First, however, it should; be understood that, for theembodiment now described windings [3a, [3b, and Home composed of adifferent number of turns of wire so that energization of the respectivewindings produces a different amount of attractive magnetic force. Oneof the six string H- actuates a difierent one of the six pairs ofcontacts IS-18, IS -18", 92+, 92'94, 95-418, and 96'--98-' in themannershown in Figure 3. Thus each character key arm has one or moreextensions such as 31, H3, and I0 (see Figure l) overlying the stringwhich itsis to actuate. Where a given key bar does not have such anextension overlying a particular string, then depression of thecharacter key associated with particular bar will not touch the saidparticular string.

Each-relay or electromagnet winding may be connected to the energizingsource by one of two paths. One path (the lower path in Figure 5) isrendered active when the lower case or nonshift letters or symbols aretyped while the other path (the-upper path denoted by the primenu-mhersin Figure 5) is rendered active when the shift key 3 (see Figure 1 isdepressed. Where a given path is rendered active, the closing of thepair of contacts actuated by the strings II will energize the associatedelectromagnetic winding but not otherwise (i. e., if it is not active).A ganged group of switches I00, I, I02, I02, I04, and I04 are located inthe same paths respectively as relay actuation switches 16-48, I6-'I8',92-94, 9294', 96-98, and 96'-98'. When the ganged switches are in theirlowered position as shown in Figure 5, then the closing of theelectromagnetic actuation switches in the lower path will have no effectbut will have an effect in the upper path since then the electromagneticwindings have a complete path to the energizing voltage source throughthe electromagnetic actuation switches and the contacts of the gangedswitches. The ganged switches are placed in this lower' position bydepression of the conventional shift key 4. (See Figure 1.) A projection8 is soldered or otherwise connected to arm I of shift key 4 whichdepresses an arm I2 to which the ganged contacts are connected. Theganged switches are housed in any suitable housin I2 which is located incontainer 2 which, as previously stated, is placed beneath the keys ofthe typewriter. Ganged switches are normally held in an upward positionby any suitable means such as a spring (not shown). Thus, differentspacing may result by depression of a single key through operation ofthe shift key. Since the upper and lower case letters are usually ofdif- 'ferent width, this type of circuit is required for the embodimentshown in Figures 1-5.

If the separate energization of windings I3a, I31), and I3c produces 1,2, and 4 units of carriage movement, then 3, 5, 6, and '7 units ofspacing may be accomplished by simultaneously energizing two or threewindings in different combinations. In the embodiment shown in Figures1-5, a minimum number of 6 pairs of contacts and 6 threads or bars IIare needed for 3 to 7 spacing selections because the same contacts areactuated whether the upper or lower case letters of a given characterkey are selected. Figure 6 discloses a switching system whichappreciably simplifies the number of components needed to effect thesame results as the embodiment of Figures 1-5 where the typewriter isthe type where the type bars are lowered rather than the carriage beingraised to effect the typing of upper case or capital letters as in mostpresent day machines.

In the embodiment shown in Figure 6, only three pairs of contacts areneeded. Each pair controls the energization of one of the windings I3a,I31), and I3c of electromagnet I3. The movable contacts I6, 92, and 96,respectively, are glued or otherwise connected to resilient arms I I6,H6, and I I6, respectively, which normally hold the attached contactsdisplaced from the associated contacts I8, 94, and 98. The aboveelements are connected by any suitable means to a plate member I08 whichmay be connected to the type bar guide member 31. Type bar guide member31 is found on most typewriters and includes a pair of guide arms I86which engage and guide the arms (such as arm I20) to which the type bars(such as IIO) which carry the raised type surfaces are connected. Theresilient contact carrying arms II6, H6, and H6 jut out into the generalpath of the type bars but are placed to avoid. being struck by the sidefaces of the type except where projections extend from the side thereof.Thus, as shown in Figure 6, an upper group of projections III, and I I2protrudingfrom the side of a type bar H0 is shown pressing againstcontact carrying arm members H6 and H6. This closes the pair of contactsI6 and T8, and 92 and 94 which, in turn, causes two of the windings I31;and I3b to be energized. If windings I3a and I3!) individually cause 1and 2 units respectively of carriage movement, then their combinedenergization causes a 3 unit movement of the carriage. The upper groupof contacts control the energization of electromagnet I3 during theupper case or shift operation of the typewriter. During the nonshiftoperation, if the switches and type projections are suitably placed, theupper group of projections III and H2 are removed from contact withcontact carrying arm members H6 and H6 and the lower group of type barprojections H3, H4, and H5 are moved into engagement with the contactcarrying arm members H6, H6, and II6". This simultaneously closes all ofthe contact pairs so that the maximum spacing results for the upper caseletter typed during the shift operation. Of course, the number ofprojections in the upper and lower groups depends on the sizesrespectively of the non-shift and shift (the upper and lower)characters.

The relay or electromagnet I3 shown in Figure 1, as previously stated,operates by providing different levels of magnetic force whichaccordingly move the lever arm member i4 and the ratchet mechanismassociated therewith an amount proportional to this magnetic force.

Figure 7 discloses electromagnetic apparatus I66 of a slightly differentcharacter than that shown in Figures 1 and 2. In this apparatus theamount of movement imparted to the ratchet mechanism 23 is notnecessarily related to the amount of magnetic force developed by theelectromagnetic apparatus but, like Figure l, is re lated to theenergized condition of the apparat-us. Thus, electromagnetic apparatusI60 consists of three windings I21, I3 I and I34 which are energized bythe depression of the character or spacing keys of a typewriter, eithersingly or in combination in the same manner as the three windings I3a,[3b, and I3c of electromagnet I3 in Figures 1 and 2. Thus, the same kindof switch devices shown in Figures l-6 may be used with the apparatusshown in Figure '7. The windings 221, I3I, and I35 are wound on separatecoil forms I26, I30, and I33, respectively. Each coil unit is mademovable with respect to the other to form separate distinct relay unitsI22, I23, and I224. The three units are mounted one next to the otherabout a common axis. Each relay unit includes a core movable relative toits associated winding. The cores of relays I23 and I24 move upward whenthe associated relay is energized and in so doing, bodily moves with itall of the relay units above it. This arrangement in effect provides foras many as seven distinct amounts of movement of lever I5I connected tothe core of top relay I22. In the embodiment of Figures 1 and 2, avariation in line voltage used to energize windings I3a, I31), and I30of electromagnet I3 would vary the amount of movement of the carriagekeeping all other conditions constant. This is not so with the apparatusshown in Figure '7.

A more detailed description of the operation and construction of theapparatus of Figure '7 will now be explained.

The top relay unit I22 includes windings i2? wound about a cylindricalcore I26 made of any suitable insulating material. The movable core ofrelay I22 includes a cylindrical member I36 made of any suitablenon-magnetic material and a magnetic member I40 cemented orotherpocketor opening in the top portion of a cap member M6, the topportion of which abuts and supports the coil form 225, etc. of relayI22. When current is passed through windings: iii of relay I22, themagnetic core member Hill is attracted upwardly toward the main portionof coil form I22 into the position shown in Figure 8. An annularshoulder I62 is provided on magnetic member MG to limit the upwardmotion of magnetic member Hi3- as it abuts the bottom of coil form I 26.The amount of upward movemerit-of magnetic member Ice caused byenergization of relay I22 is determined by the initial distancebetweenthe' top of shoulder I62 and the bottom of the coil form I2against which it abuts when moved upwardly by the magnetic force ofrelay I22. Cylindrical core member 536 moves with magnetic member Hilland in so doing, raises an arm member i5 3 connected with it. One endI5I of lever I51; which pivots about a pin I52; is connectedto armmemberI59 so that an upward movement of end lei causes a downward movement ofthe other end I5! of lever I55 The end it of lever i5i is coupled toracl: member 23- in a manner to be described so that energization ofrelay 22 moves rack member 23 downward. The de-energization of the relayunits'cause. rack 23 to move upwardly under the force of spring 25 tomove the carriage in the same manner described in connection with theapparatus shown in Figures 1 and 2.

Cap member I 36, it should benoted, does not move at all if only relayH2 is energized. The latter member is connected to the cylindrical coremember I3? of the relay I23- .which is just below relay i22.Energization of relay i 2-3 results in anupwardmovementof cylindricalcore member i331 ina manner similar to that described in connection withthe movement of core member. I33 of relay 522} which raises cap memberMather-cwith. This raises the entire relay I22 with it. A magnetic'member Mi similar to magnetic member Hit: it fixedly connected tothebottom of coremember l3? and normally rests in a pocket formedinacapmember I 57 associated with relay I25. The distance iromthe annularshoulder i64 of magnetic member Hi to the bottom portion of coil formi38 (when relay i233 isde-energized) is made greater than the equivalentdimensions associated with the components of relay i22. Thereforewhen-only relay IE3 is energized, the core of relay I23 includingelements IEI, I37, andcap-member I48 is raised a greater amount than thecore of relay IZZWhen-thelatter relay is alone energized as beforedescribed. Since the entire relay IZZ is raised withthe core of relayI23, it-can be seen that energizationof relay I23 alone will raise endIEI of lever I5I a greater amount than if only relay I2-2-wereenergizedthereby providinggreater letter spacing.

If relays I22 and I23" were both energized together, then itshouldbeclear that the amount of upward movement of end IEI of lever I5Iwill be equal to the sum of the efi'ects of the individual coremovements of relays I22 and I23 Relays I24 including cap member I41,cylindrical core member I38; and magnetic member l i2 is similar to thestructure and operation ofthe analogous components of relays I22 andI23. Since no relay is located below relay I24, magnetic core member I42of relay I2 normally (when relay IN is deeenergi zedj rests in thepocket of a stationary base member MS.

It is desired that theen'ergization of relay I-EQ alone should result ina greater amount of movement of lever li'iI' than energization of eitherrelays E22 or [23 alone. distance from the shoulder I65 to the bottom ofthe coil form- I33: of relay i2 1 (when the latter rclayistie-energized) is accordingly made greater than the analogous dimensionsof relays I22 and I23.

Figure '7- shows the condition of the electromagnetic apparatus 666'when. only relay I24 is energized. I

As long as the voltage applied to the relays I22, I23, and I2 3sufficiently large to pull the respective magnetic core members I49, MI,and M2- intoabutting relationwith the bottom of the associated coilforms,- the apparatus will operate consistently and accurately.

Needless to say, the amount of movement of raclrmember 23 will be thesum of the individual results of each relay unit.

The embodiment of Figure '7 includes novel line spreading apparatuincorporated into the spacing apparatus there showns 'I'hllfi; thepointat which the bottom portion ofrack member- 23 connects with lever I51 ismade variable with the amount of line; spread desire,d. The closer thisconnection pointiis to the pivot point I5 2 cf lever I58, the smallerthe amount of downward motion results from a given upward motionoi therelay apparatus. Aslot I E lis formed in the end of lever I50 adjacentrack member 23 and a bolt I53 or other suitable adjustable connectingmean passes through slot I54 and a hole in the lower portion I56 of'rackmember 23' and is held in place by a nut (not shown)v threaded to theother end of bolt I53. The frictiorl'of the head ofbolt lbltagainst thesurface of lever l5! when the nut connected thereto is tightenedsufficiently to prevent sliding of' the bolt I53 is slot I54. 7 Rackmember 23 is, however; able to rotate a little about bolt I53 as leverI5lis moved about pivot point I521 Lower portion I58 of rack member 23'is pivoted to the upper porti'onther'eof by means of a suitable pivotjoint I55 so that the portion of rack member 23 carrying the toothedportions can" freelysli'de' between vertical guides I5. The motion ofthe toothed portion of rack member 231's thereiore'a linear motion.

A previously stated, many. modifications may be made of thepreferred'forms' of "the instantiavention above described withoutdeviating from the spirit and broader scope of the instant invention. I

For example, electronic switches could be substitute'd for themechanical switch arrangement shown in Figure 6. In such case, each ofthe projections on the type bar I 10 could be replaced by a small lightsource" (broadly taken), such as a small circular" area of white paintwhich reflects more light than the adjacent type bar surface or a smallarea of radium paint. The mechanical switches could each .be-replaced bya phototube or other suitable light detector which energizes one of therelay windings as the light source moves adjacent the phototube;

Although the back spacing systemshown in Figures I and 2 is especiallysuitable for an electrically proportional spacing? typewriter as thereshown; it could be'adapted Withi advantage to evenmechanicallyproportional pacing apparatus where rack member 23 ismechanically rather than electrically moved.

, There are numerous ways to ensure that the lead screw 33 will alwaysbe in a position to return to a rotary position such that the carriagearm 22 will engage the lead screw slot when the -carriage is at the lefthand margin position. For example, the shaft could be spring biased insuch a manner that when arm 22 is raised from the lead screw (thefriction between the arm 22 and the screw could be made sufficiently toprevent rotation of the screw by the biasing spring), the said screw isfree to rotate a small amount under the force of the spring to a fixedpredetermined position. Since such a spring-biased shaft arrangement isobviously old in the art (for example, such an arrangement is found inthe cylinders supporting the common draw shade), it is felt unnecessaryto describe the details of such a spring biasing arrangement.

The instant invention thus provides a new and improved proportionalspacing device which is relatively simple and inexpensive to use andwhich is especially adaptable for use in converting fixed spacingtypewriters to variable spacing typewriters.

We claim:

1. In combination with the carriage and key mechanism of a typewriter, agear means coupled to said carriage to move same a distance proportionalto the movement thereof, a rack member having first and second toothedportions extending on opposite sides of said gear means for anengagement with the teeth thereof to move said gear means, said toothedportions of said rack member being spaced to allow engagement of onlyone toothed portion at a time with said gear means, said first toothedportion normally in engagement with said gear means during forwardmovement of said carriage, means actuated by the back space keymechanism of said typewriter to move said first toothed portion of saidrack member out of engagement with said gear means and to simultaneouslymove said second toothed portion thereof into engagement with said gearmeans, rack actuation means coupled between the character key mechanismof said typewriter and said rack member to move the toothed portionsthereof an amount proportional to the size of the letter printed by theparticular key struck, and letter blanking means actuated by the backspace key for preventing the printing of any letters as a character keymechanism is operated during a back spacing operation.

2. The combination of claim 1 characterized further by said gear meanscoupled to said carriage through a fixed feed screw rotated directlythereby and a feed screw thread engaging arm extending from the carriageto abut the sides of the feed screw threads and be moved thereby as saidfeed screw is rotated.

. prevent same from striking the typewriter paper.

5. The combination of claim 1 characterized further by said rackactuation means comprising an electromagnet for imparting rotation tosaid rack member, a source of electrical energy for said electromagnet,and electric contact means coupled between said source of electricalenergy and electromagnet and actuated by the character key mechanism ofsaid typewriter to energize said magnet to a degree proportional to thedesired spacing, said rack member being in cooperative relation withsaid electromagnet so as to be movable an amount proportional to thedegree of energization of said electromagnet.

6. The combination of claim 5 characterized further by said electricalcontacts being mounted on an insulating support member mounted adjacentthe type bar guide member, said contacts being mounted for actuation byprojections on the side faces of the type bar.

7. The combination of claim 1 characterized further by said gear meanscomprising first and second ratchet wheels mounted on a common shaft andhaving teeth of opposite type for rotation in opposite directions whenengaged by the first and second toothed portions of said rack member,said first toothed portion of said rack member mounted adjacent one ofsaid ratchet wheels and the said second toothed portion mounted adjacentsaid other ratchet wheel.

8. In combination with the carriage and character key mechanism of atypewriter, proportional spacing apparatus comprising an electromagneticmeans for imparting motion to said carriage, ratchet mechanism includinga rotatable ratchet wheel and a pawl means spring biased for rotatingsaid ratchet wheel in only a first direction, said pawl means beingmovable by said electromagnetic means to a degree proportional to thedegree of energization thereof, electrical contacts mounted foractuation by the character key mechanism of said typewriter forselecting the level of energization of said electromagnetic means, andmeans converting the rotary motion of said ratchet wheel to longitudinalmotion of said carriage.

9. In combination with the carriage and character key mechanism of atypewriter, proportional spacing apparatus comprising electromagneticmeans for developing a selectively variable attractive force, firstmeans including a portion made of a magnetic material mounted formovement in an amount determined by the magnitude of magnetic force ofsaid electromagnetic means, second means for coupling the motion of saidfirst means to said carriage, and third means actuated by the characterkey mechanism of said typewriter for causing said electromagnetic meansto develop a magnetic force proportional to the width of the characterstruck.

10. Apparatus for converting a fixed spacing typewriter having acarriage, character keys, and a carriage release key to a proportionalspacing typewriter comprising a box beneath said typewriter containing aplurality of oblong switch actuation members extending transversely ofand beneath the character key arms of said fixed spacing typewriter andrespective electrical contacts coupled to said switch actuation membersfor actuation thereby, a spiral threaded screw rotatably mounted to thestationary frame of said fixed spacing typewriter; an arm extending fromthe carriage of said typewriter and engaging the sides of the threads ofsaid screw for movement in response to rotation of said spiral screw;electromagnetic means adapted to be energized to a plurality ofdiiferent conditions for moving said carriage varying amounts; means forcoupling said electrical contacts between said electromagnetic means anda source of energizing voltage; the condition of said electromagneticmeans determined by the selection of the contacts to be actuated by saidswitch actuation members; said character key arms including portionswhich abut the particular switch actuation members upon depression ofsaid key arms to produce the desired condition of said electromagneticmeans; lever means including a toothed portion on the end thereofmounted for movement by said electromagnetic means an amount variablewith the energization condition of said electromagnetic means; and gearmeans coupled to said spiral screw for rotating same and mounted forengagement with and rotation by the toothed portion of said lever meansin an amount varying with the amount of movement of said lever means.

11. The combination of claim 8 characterized further by said electricalcontacts mounted on an insulating supporting member adjacent the saidcarriage of the typewriter, said electrical contacts comprising aplurality of normally opened pairs of contacts having projectingportions extending into the path of movement of the type bars of thetypewriter, and projections on the side of the type bars of saidtypewriter for abutting the projecting portions of the contact pairsproducing the desired letter spacing.

12. In combination with the carriage, type bars and type bar guidemember of a typewriter, proportional spacing apparatus comprising aplurality of space selecting elements for moving said carriage differentamounts after the typing of a letter, a plurality of electric contactpairs for connecting a source of energizing voltage to said spaceselecting elements mounted adjacent said type guide member, said contactpairs each having a projecting portion extending into the general pathof movement of the said type bars for actuating the associated contactpair when engaged by a projection on said type bars, and projections onsaid type bars positioned for engagement with the appropriate projectingportion of said contact pairs to select the proper space selectingelement for energization depending on the width of the letter justtyped.

13. In combination with the carriage and type bars of a typewriterhaving two characters printable by the depression of a single characterkey by means of a shift key mechanism which varies the vertcial positionof the type bars, proportional spacing apparatus comprising a pluralityof space selecting elements for moving said carriage different amountsafter the typing of a letter, a plurality of electric contact pairs forconnecting a source of energizing voltage to said space selectingelements, said contact pairs each having a projecting portion extendinginto the general path of movement of the said type bars for actuatingthe associated contact pair when engaged by a projection on said typebar, and two vertically spaced groups of projections on said type barsfor engagement with the appropriate projecting portions of said contactpairs respectively only during shift and non-shift operation of thetype- 14 writer to select the proper space selecting elements forenergization depending on the width of the letter just typed.

14. In combination with the carriage and character key mechanism of atypewriter, proportional spacing apparatus comprising a plurality ofaxially displaced, contiguous coaxial electrical relay coils mounted formovement along their common axis, a separate core in each relay axiallymovable a fixed amount in the same direction relative to its associatedcoil as same is energized, respective means assiciated with the coils ofthe said relay coils for bodily moving the next successive relay coiland its core simultaneously with movement thereof, linkage means coupledto the core of the last successive relay for moving said carriage anamount proportional to the total displacement thereof, respectiveelectrical contacts connected to said respective relay coils forconnecting a source of voltage thereto to energize same, and meansresponsive to depression of said character key mechanism to actuate theparticular electrical contacts which will cause a movement of saidcarriage proportional to the width of the letter just typed.

15. The combination of claim 14 characterized further by said linkagemeans including a pivoted lever coupled to the core of the said lastrelay, the distance of the free end thereof from the point of pivotbeing gradually variable whereby variable line spreading is provided.

16. In combination with the carriage and key mechanism of a typewriter,variable spacing apparatus comprising electromagnetic means fordeveloping a force to move said carriage, a plurality of pairs ofelectrical contacts for coupling a source of energizing voltage to saidelectromagnetic means to vary the energization thereof, as determined bythe particular pairs of contacts which are closed, means actuated by thecharacter keys of said typewriter for closing the particular electricalcontact pairs which will develop a level of energization in saidelectromagnetic means proportional to the width of the character struck,and means including a lever pivoted intermediate its ends with one endcoupled to said carriage, said lever being movable an amountproportional to the degree of energization of said electromagnetic meansto move said carriage a distance proportional to the width of a letterjust typed, the distance between the end of said lever coupled to saidcarriage and the point of pivot of the lever being variable whereby linespreading is provided.

ERIK FREY. RUSSELL E. HATTIS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,349,470 Jackson Apr. 13, 1948 2,487,373 Reppert Nov. 8, 1949

